UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


BROWN  ROT  OF  APRICOTS 

By  W.  L.  HOWARD  and  W.  T.  HORNE 


DECIDUOUS    FRUIT    STATION,     MOUNTAIN    VIEW,     SANTA    CLARA    COUNTY 

Offices,  laboratory  and  garage  partially  concealed  by  the  large  pepper  tree  at  the 
side  of  the  residence.     Established  January  1,  1920. 


BULLETIN  No.  326 


UNIVERSITY   OF  CALIFORNIA  PRESS 

BERKELEY 

1921 


David  P.  Barrows,  President  of  the  University. 

EXPERIMENT  STATION  STAFF 

HEADS  OF  DIVISIONS 

Thomas  Forsyth  Hunt,  Dean. 

Edward  J.  Wickson,  Horticulture  (Emeritus). 

Walter  Mulford,  Forestry,  Director  of  Resident  Instruction. 

C.  M.  Haring,  Veterinary  Science,  Director  Agricultural  Experiment  Station. 

B.  H.  Crocheron,  Director  of  Agricultural  Extension. 
Hubert  E.  Van  Norman,  Vice-Director;  Dairy  Management. 

James  T.  Barrett,  Acting  Director  of  Citrus  Experiment  Station;  Plant  Pathology 
William  A.  Setchell,  Botany. 
Myer  E.  Jaffa,  Nutrition. 
Ralph  E.  Smith,  Plant  Pathology. 
John  W.  Gilmore,  Agronomy. 
Charles  F.  Shaw,  Soil  Technology. 
John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 
Frederic  T.  Bioletti,  Viticulture  and  Fruit  Products. 
Warren  T.  Clarke,  Agricultural  Extension. 
John  S.  Burd,  Agricultural  Chemistry. 
Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 
Ernest  B.  Babcock,  Genetics. 
Gordon  H.  True,  Animal  Husbandry. 
Fritz  W.  Woll,  Animal  Nutrition. 
W.  P.  Kelley,  Agricultural  Chemistry. 
H.  J.  Quayle,  Entomology. 
Elwood  Mead,  Rural  Institutions. 
H.  S.  Reed,  Plant  Physiology. 
L.  D.  Batchelor,  Orchard  Management. 
J.  C.  Whitten,  Pomology. 
IFrank  Adams,  Irrigation  Investigations. 

C.  L.  Roadhouse,  Dairy  Industry. 
R.  L.  Adams,  Farm  Management. 

F.  L.  Griffin,  Agricultural  Education. 
John  E.  Dougherty,  Poultry  Husbandry. 
W.  B.  Herms.  Entomology  and  Parasitology. 
L.  J.  Fletcher,  Agricultural  Engineering. 
Edwin  C.  Voorhies,  Assistant  to  the  Dean. 


fin  co-operation  with  office  of  Public  Roads  and  Rural  Engineering,  U.  S.  Department  of  Agriculture. 


BROWN    ROT  OF  APRICOTS 

By  W.  L.  HOWARD  and  WM.  T.  HORNEi 


Brown  rot  is  a  fungus  disease  affecting  apricots  and  various  other 
stone  fruit  trees.2  It  attacks  both  the  ripening  fruit  and  the  twigs; 
but  since  the  attack  on  the  ripening  fruit  is  serious,  it  is  to  this  attack 
that  reference  is  made  when  speaking  of  the  brown  rot.  In  Califor- 
nia, however,  the  attack  on  the  twigs  has  attracted  more  attention. 
In  this  the  withering  flowers  become  infected  and  not  only  the 
blossoms  and  young  fruits  are  killed  but  also  the  twigs  to  a  distance 
of  several  inches.  Atmospheric  moisture  favors  the  growth  of  the 
fungus,  which  forms  spores  in  gray  pustules  of  about  the  size  of  a 
pin  head  on  rotting  fruit  and  on  blighted  flowers  and  twigs.  In 
California  it  is  practically  confined  to  the  regions  exposed  to  ocean 
influences  and  does  not  develop  except  in  times  of  unusually  moist 
weather. 

On  the  basis  of  numerous  experiments  and  observations  as  to  the 
best  way  of  treating  this  disease,  the  University  of  California  has 
recommended  a  thorough  cleaning  out  of  all  blighted  twigs  and  rotted 
fruits  of  the  preceding  year,  to  be  followed  by  a  spray  program 
consisting  of  two  applications  of  winter  strength  lime-sulphur  solution 
in  quick  succession  just  before  blossoming  and  a  third  spray  of 
summer  strength  lime-sulphur  solution  while  the  calyxes  or  jackets 
are  still  on  the  fruit. 

As  this  program  seemed  unduly  burdensome,  a  new  set  of  experi- 
ments was  commenced  by  the  University  at  the  Deciduous  Fruit 
Station  at  Mountain  View,  Santa  Clara  County.  These  experiments 
give  hope  of  a  simpler  control  method,  and  it  seems  advisable  to  make 
a  progress  report  of  the  work. 

The  experiments  were  started  in  February,  1920.  Sixteen  differ- 
ent spray  treatments  were  tried,  and  the  results  for  the  one  season 
were  so  pronounced  as  to  justify  the  conclusion  that  apricot  blossoms 
may  be  effectively  protected  from  brown  rot  by  spraying  the  trees 


i  The  work  described  in  this  bulletin  was  planned  by  the  authors  jointly,  but 
was  carried  out  by  the  senior  author  and  this  statement  of  the  results  was  prepared 
by  him.     The  plates  were  arranged  by  the  junior  author. 

2  The  fungus  causing  this  disease  is  now  generally  known  as  Sclerotinia  cinerea 
(Bon.)  Wor.,  but  is  found  in  older  works  in  this  country  under  the  names  Scl. 
fructigena  (Pers.)  Schroet.  and  Monilia  fructiaena  Pers. 


74  UNIVERSITY  OF  CALIFORNLY EXPERIMENT  STATION 

once,  shortly  before  they  come  into  bloom,  with  either  lime-snlphur 
or  Bordeaux  mixture.  The  lime-sulphur  should  be  used  at  the  rate 
of  1  gallon  to  9  gallons  of  water,  and  the  Bordeaux  mixture  at  a 
strength  of  4—5-50  (4  pounds  bluestone,  5  pounds  fresh  stone  lime, 
50  gallons  water).  Apparently  the  so-called  dry  lime-sulphur,  used 
at  the  rate  of  12  pounds  to  50  gallons  of  water,  is  quite  as  effective 
as  either  of  the  other  two  sprays  mentioned. 

The  period  of  effective  spraying  is  short.  In  the  experiment,  the 
best  results  followed  spraying  when  the  buds  were  considerably 
swollen.  However,  the  protection  against  the  disease  was  excellent 
when  spraying  was  done  at  the  time  the  trees  were  coming  into  bloom. 
Apparently  there  is  no  injury  to  the  flowers  if  the  spraying  is  done 
after  they  are  fully  open.  The  experiments  showed  conclusively  that 
spraying  after  the  trees  have  begun  to  go  out  of  bloom  is  too  late  to  be 
of  much  value.  The  disease  apparently  attacks  the  flowers  after  they 
are  fully  open.  Spraying  after  the  blooming  period  therefore  is  too 
late,  as  infection  has  already  taken  place.  As  with  treatments  for 
most  diseases,  spraying  against  the  brown  rot  is  a  preventive  rather 
than  a  cure. 

No  evidence  has  been  secured  to  show  that  spraying  apricot  trees 
before  the  buds  begin  to  swell  affords  any  protection  against  the 
disease.  It  may  be  assumed  therefore  that  early  winter  spraying 
against  the  brown  rot  is  useless. 

Normally,  apricot  trees  in  the  Santa  Clara  Valley  come  into  bloom 
in  from  seven  to  ten  days  after  the  buds  are  swollen  sufficiently  to 
show  the  white  lines  where  the  bud  scales  have  expanded  to  accommo- 
date the  growth.  In  regions  near  the  ocean,  such  as  the  Pajaro  Valley, 
in  Santa  Cruz  County,  and  the  Aromas  district,  in  Monterey  County, 
the  blooming  season  may  be  very  irregular.  During  the  season  of 
1920  many  orchards  had  a  blooming  period  lasting  from  two  to  four 
weeks.  Under  such  circumstances,  when  the  first  flowers  begin  to 
open  on  any  given  tree,  a  majority  of  the  buds  will  probably  show 
little  or  no  signs  of  growth.  The  best  recommendation  that  can  be 
made  for  meeting  these  conditions  is  to  commence  the  spraying  when 
the  first  considerable  number  of  flowers  are  opening.  While  a  spray 
at  this  time  might  not  afford  the  fullest  protection  to  the  latest  buds, 
it  would  undoubtedly  protect  a  great  majority  in  their  different  stages 
of  development.  To  delay  the  spraying  until  the  most  forward  flowers 
have  passed  out  of  bloom  simply  invites  infection,  while  spraying  as 
the  forward  ones  are  coming  out  of  bloom  completely  protects  those 
that  are  fully  open,  and,  in  greater  or  less  degree,  also  protects  those 
that  are  not  yet  open. 


Bulletin  326 


BROWN  ROT  OF  APRICOTS 


75 


Fig.   1. — Severe  case  of  brown  rot  twig  blight  on  apricot  tree  showing  many 
dead  twigs  and  shoots.     Photographed  by  Miss  E.   H.   Phillips,   April  23,  1917. 


76  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


THE    SPRAYING    EXPERIMENTS 

Since  the  brown  rot  does  its  chief  harm  by  attacking  the  apricot 
trees  when  in  bloom,  killing  not  only  the  blossoms  but  the  entire  fruit 
spurs  as  well,  a  spraying  experiment  was  planned  to  find  what  mater- 
ials would  protect  the  flowers  from  infection,  and  at  what  time  or 
times  they  should  be  applied.  Experiments  carried  on  in  previous 
years  by  the  Division  of  Plant  Pathology  of  the  University  of  Cali- 
fornia indicated  that  lime-sulphur  might  be  a  good  fungicide  for 
the  purpose  if  three  sprayings  were  given,  beginning  when  the  buds 
were  swelling  and  ending  as  the  trees  were  going  out  of  bloom. 
Taking  this  information  as  a  starting  point  in  the  experiment  begin- 
ning in  February,  1920,  the  trees  were  sprayed  at  three  stages  of 
development,  namely:  when  the  buds  were  swelling,  when  the  buds 
were  opening,  and  when  the  flowers  were  falling.  The  test  included 
the  following  materials :  lime-sulphur,  Bordeaux  mixture,  crude  oil 
emulsion,  distillate  emulsion,  dry  lime-sulphur,  dry  sulphur  (as  a  dust 
spray),  and  lime  whitewash. 

The  lime-sulphur  was  used  at  the  standard  winter  strength  of 
1  gallon  to  9  gallons  of  water  when  used  as  a  dormant  spray,3  and 
1  gallon  to  29  gallons  of  water  when  used  as  a  summer  spray.  In 
one  test  the  lime-sulphur  was  used  at  half  strength.  The  Bordeaux 
mixture  was  used  at  a  strength  of  4-5-50  (4  pounds  copper  sulphate, 
5  pounds  fresh  lump  lime,  50  gallons  water)  and  also  at  a  strength 
of  1 3^-2^2-50,  both  being  dormant  sprays.  Crude  oil  emulsion  was 
used  at  the  rate  of  15-100  (15  gallons  of  the  emulsion  and  water  to 
make  100  gallons)  ;  this  was  a  dormant  spray.  The  distillate  emulsion 
was  used  at  a  strength  of  15-200  (15  gallons  of  the  emulsion  and 
water  to  make  200  gallons).  The  dry  lime-sulphur  was  used  at  the 
rate  of  12  pounds  to  50  gallons  of  water  as  a  dormant  spray,  and 
21/2  pounds  to  50  gallons  as  a  summer  spray.  The  lime  whitewash 
was  made  by  the  following  formula :  lime  10  pounds,  sulphur  2  pounds, 
salt  y2  pound,  the  salt  and  sulphur  being  stirred  in  while  the  lime 
was  slaking.  Water  was  added  until  the  proper  consistency  for 
spraying  was  attained.  The  dry  sulphur  was  a  brand  known  as 
"ventilated"  sulphur,  which  is  perhaps  the  best  grade  for  dusting 
purposes. 

The  applications  given  during  the  first  two  stages  (when  buds 
were  swelling,  and  when  buds  were  opening)   were  regarded  as  dor- 


3  Spray  applied  as  first  blossoms  were  opening  was  classed  as  a  dormant  spray, 
since  spray  of  winter  strength  caused  no  injury  at  this  stage,  i.e.,  before  the 
leaves  were  out. 


Bulletin  326  BROWN  ROT  OF  APRICOTS  77 

mant  sprays  and  the  materials  were  used  at  winter  -strength.  At 
the  third  stage  (when  flowers  were  falling)  the  trees  were  looked 
upon  as  being  in  a  growing  condition,  as  the  leaf  buds  were  then 
about  to  open,  so  the  sprays  were  diluted  to  summer  strength. 

In  addition  to  the  single  sprayings  given  at  the  three  stages 
mentioned,  certain  rows  were  sprayed  three  times,  that  is,  at  all  three 
of  the  different  stages.  When  three  sprayings  were  given,  the  first  two, 
as  before  stated,  were  at  winter  strength  and  the  third  at  summer 
strength. 

All  the  apricots  in  the  spraying  experiment  were  of  the  Blenheim 
variety.  The  trees  were  about  twenty  years  old,  of  fair  vigor  con- 
sidering the  short  rainfall  of  the  winters  of  1919  and  1920,  and  had 
been  bearing  average  crops.  They  did  not  show  much  indication  of 
having  suffered  seriously  from  the  brown  rot  in  previous  years. 

Almost  up  to  the  day  when  the  first  spraying  was  done,  the 
weather  had  been  too  dry  to  favor  the  growth  of  the  disease.  When 
first  sprayed,  the  buds  had  been  showing  signs  of  growth  for  several 
days;  they  were  swollen  so  that  the  white  streaks  caused  by  the 
slipping  of  the  bud  scales  were  very  noticeable.  The  rains  began  as 
the  spraying  started,  and  continued  intermittently  until  several  days 
after  the  last  applications  were  made.  The  work  was  done  with 
a  barrel  sprayer  and  a  common  Bordeaux  nozzle.  The  pressure  per- 
haps did  not  average  much  above  75  pounds,  although  at  times  it 
ran  as  high  as  125  pounds.  All  parts  of  the  trees  were  covered,  from 
three  to  three  and  one-half  gallons  of  material  per  tree  being  used. 
The  results  of  the  spraying  are  shown  in  the  tables  which  follow : 


TABLE  I 

Trees  Sprayed  as  Buds 

were  Swelling 

Spray  treatment 

Spraying 
date 

Average  no. 

diseased  twigs 

per  tree 

Efficiency  of 

treatment, 

per  cent 

Eow 

3 

Lime-sulphur  1-10 

Feb.  17 

6 

92.3 

Eow 

4 

Bordeaux  mixture  4-5-50 

Feb.  17 

6 

92.3 

Eow 

9 

Crude  oil  emulsion  15-100 

Feb.  21 

15 

80.7 

Eow 

10 

Bordeaux  mixture  l%-2%-50 

Feb.  21 

9 

88.4 

Eow 

16 

Distillate  emulsion  15-200 

Feb.  23 

94 

—20.0 

Eow 

1 

Unsprayed  row 

78 

TABLE  II 

Trees  Sprayed  as  Buds 

i  were  Opening 

Spray  treatment 

Spraying 
date 

Average  no. 

diseased  twigs 

per  tree 

Efficiency  of 

treatment, 

per  cent 

Eow 

5 

Lime-sulphur  1-10 

Feb.  28 

7 

90.4 

Eow 

7 

Bordeaux  mixture  4-5-50 

Feb.  28 

9 

87.6 

Eow 

12 

Dry  lime-sulphur  12-50 

Feb.  28 

8 

89.0 

Eow 

15 

Unsprayed  row 

73 

78  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


TABLE  III 

Trees  Sprayed  as  Flowers  were  Falling 

Average  no. 
Spraying            diseased  twigs 
Spray  treatment                                                    date                      per  tree 

Lime-sulphur  1-30                                 March  10                  39 

Efficiency  of 

treatment, 

per  cent 

55.6 

Bordeaux  mixture  l%-2%-50            March  10                  60 

31.8 

f  March     2  | 
Sulphur  dust                                         \        and        \              47 

[March  10  J 

53.4 

Lime  whitewash                                      March  17                128 

—45.4 

Eow     6 
Bow  13 

Bow  14 

Bow  18 

Bow  19     Unsprayed  row*  88 

*  This  row  was  later  (May  25)  sprayed  with  self -boiled  lime-sulphur.  This 
was  long-  after  the  brown  rot  had  ceased  to  be  active,  so  that,  for  statistical  pur- 
poses, this  may  be  regarded  as  an  unsprayed  row. 


TABLE  IV 

Sprayed  Three  Times  :  As  Buds  were  Swelling,  As  Buds  were  Opening, 
As  Flowers  were  Falling 

Average  no.      Efficiency  of 
Spraying      diseased  twigs     treatment, 
Spray  treatment  date  per  tree  per  cent 

fFeb.  17  1 
Bow     2     Lime-sulphur  1-10;   1-10;   1-30  <{  Feb.  28       \  4  94.7 

[March    10  J 

[Feb.  17  1 
Bow     8     Lime-sulphur  1-10;   1-10;   1-30*        ]  Feb.  28       I  7  93.7 

[March    10  J 

fFeb.  17  1 
Bow  17     Lime-sulphur  1-20;   1-20;   1-60  ]  Feb.  28       I         12  84.2 

[March    10  J 

fFeb.  21  1 
Bow  11     Dry  lime-sulphur  12-50;   12-50;  j  Yeh.  28       I         13  82.8 

21/2-50  [March   10  J 

Bow  20     Unsprayed  row  76 

*  Two  different  rows,  widely  separated  in  the  orchard,  were  given  the  same 
lime-sulphur  treatment. 

The  figures  show  very  clearly  that  the  disease  can  be  held  in 
reasonable  check  by  spraying,  and  that  lime-sulphur  and  Bordeaux 
mixture  at  winter  strength,  when  applied  at  the  right  time,  are  about 
equally  effective.  Each  gave  above  90  per  cent  control  when  used 
as  a  single  spray.  The  figures  also  indicate  that  spraying  as  the 
trees  are  passing  out  of  bloom  is  apparently  too  late  and  does  very 
little  good.  It  is  true  that  the  summer  strength  of  lime-sulphur  gave 
55  per  cent  protection,  but  to  be  really  efficient  a  spray  should  reduce 
disease  infection  by  75  per  cent  to  95  per  cent.  The  figures  do  not 
show  much  difference  in  the  effects  of  the  spraying  when  buds  were 
swelling  and  when  buds  were  opening.  This  is  fortunate,  as  most 
growers  will  be  forced  to  begin  their  spraying  four  or  five  days  before 


Bulletin  326  BROWN  ROT  OP  APRICOTS  79 

the  buds  begin  to  open  in  order  to  be  able  to  finish  by  the  time  the 
trees  are  coming  into  bloom.  Also  there  is  always  danger  of  delay 
caused  by  mishaps  to  equipment  and  by  rain  and  wet  ground. 

The  crude  oil  emulsion  mentioned  under  Table  I  was  included, 
not  because  it  was  thought  to  be  a  fungicide,  but  in  order  to  see  if 
it  would  cause  any  spray  injury  when  buds  were  much  swollen.  There 
was  not  a  trace  of  spray  injury,  but  this  might  be  due  to  the  fact  that 
the  spraying  was  done  in  rainy  weather.  There  were  several  days 
of  very  cold,  rainy,  and  cloudy  weather  about  this  time.  Injury 
from  oil  sprays,  which  is  now  very  rare,  is  believed  to  occur  only 
when  buds  are  quite  dormant  or  very  dry.  There  is  seldom  any  injury 
when  buds  are  beginning  to  be  active.  The  surprise  of  this  test  was 
that  the  row  sprayed  with  the  oil  emulsion  showed  very  little  brown 
rot.  Although  this  material  cannot  yet  be  recommended  as  a  brown 
rot  spray,  it  is  hoped  that  those  who  can  will  try  it  experimentally 
in  a  small  way.  If  it  should  prove  to  be  reliable  for  controlling  the 
brown  rot,  it  would  indeed  be  a  valuable  spray,  as  it  would  at  the 
same  time  rid  the  trees  of  the  brown  apricot  scale,  which  at  present 
must  be  sprayed  against  separately  every  two  or  three  years. 

It  is  very  apparent  that  the  distillate  emulsion  is  of  no  value  as 
a  spray  against  brown  rot,  and  the  lime  whitewash  spray  appeared 
to  be  worse  than  useless.  All  the  sprays  under  Table  III,  however, 
were  applied  too  late  to  do  much  good;  but  even  so,  the  whitewash 
made  the  poorest  showing  of  all  in  that  group.  It  is  unfortunate  that 
no  trees  were  dusted  with  the  "ventilated"  sulphur  in  either  of  the 
first  two  stages  of  the  buds. 

The  so-called  dry  lime-sulphur  made  a  good  showing  wherever  it 
was  tried,  and  apparently  it  is  as  reliable  as  either  the  common  lime- 
sulphur  or  Bordeaux  mixture  for  controlling  the  brown  rot. 

Table  IV,  taken  by  itself,  would  seem  to  indicate  that  three  spray- 
ings are  very  satisfactory  for  controlling  the  brown  rot,  but  from 
Tables  I,  II,  and  III  it  is  plain  that  one  spraying,  after  the  buds  are 
well  swollen  and  before  the  trees  blossom,  is  entirely  sufficient.  It 
was  this  first  or  second  spraying,  then,  or  the  combination  of  first, 
second,  and  possibly  third,  and  not  the  third  spraying  alone  that  did 
the  work.  This  is  indeed  fortunate,  as  growers  who  tried  to  spray 
their  trees  three  times  found  such  a  program  impracticable  on  account 
of  the  short  period  allowed  for  the  work  and  the  inevitable  delays  due 
to  the  weather. 


80 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


OTHER    RESULTS    FROM    SPRAYING 

All  the  trees  in  the  experiment,  both  sprayed  and  unsprayed,  had 
a  full  bloom  and  set  a  heavy  crop  of  fruit.  When  the  fruit  was 
thinned,  beginning  April  19,  it  was  noticed  that  trees  sprayed  with 
winter  strength  lime-sulphur  or  dry  lime-sulphur  were  practically 
free  from  attack  by  the  peach  twig  borer  (Anarsia  lineatella) ,  while 
those  sprayed  with  Bordeaux  and  other  materials  or  not  sprayed  at 
all  were  seriously  infested.    This  insect  is  already  present  in  many  of 


Fig.  2. — Three  Boyal  Anne  cherries  inoculated  with  the  brown  rot  fungus 
from  blighted  apricot  twigs.  The  two  fruits  below  were  punctured  with  a  sterile 
needle  at  the  same  time.  Inoculated  June  30.  Photographed  July  7,  by  Miss 
E.  H.  Phillips. 


the  orchards  that  are  badly  infected  by  brown  rot,  and  a  lime-sulphur 
spray  of  dormant  strength  shortly  before  the  trees  come  into  bloom 
is  the  only  reliable  treatment  known  for  holding  it  in  check.  It  is 
fortunate  that  this  same  spray  will  also  control  the  brown  rot.  If 
the  peach  worm  or  twig  borer  has  not  yet  appeared  in  an  orchard 
where  brown  rot  is  present,  Bordeaux  mixture  is  a  reliable  spray 
against  the  brown  rot  alone. 


Bulletin  326 


BROWN  ROT  OF  APRICOTS 


81 


DO    SULPHUR    SPRAYS    CAUSE    INJURY    TO    APRICOTS? 

There  is  a  tradition  in  some  apricot  sections,  and  especially  in 
the  Santa  Clara  Valley,  that  lime-sulphur  sprays  may  injure  the  fruit 
by  causing  it  to  be  under-sized  or  late  in  ripening.     In  the  spraying 


Fig.  3. — Blighted  twigs  of  apricot,  April  7,  1917.  Gum  shows  near  the  lower 
end  of  the  twigs.  This  is  usually  near  the  end  of  the  killed  area.  Spore  pustules 
usually  show  on  twigs  and  dead  flowers  at  this  stage  but  are  not  clearly  shown 
in  this  picture.    When  the  twig  is  cut  into  it  is  found  brown  and  dead. 


experiment  described  above,  there  was  not  a  trace  of  injury  observed 
from  any  of  the  sprays  except  the  self-boiled  lime-sulphur,  which,  at 
present,  is  not  recommended  for  apricots  at  any  time.  Even  where 
trees  were  sprayed  three  times  with  the  commercial  lime-sulphur,  the 


82  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

harvesting  records  showed  no  differences  in  time  of  ripening  or  in 
fruit  sizes  that  were  traceable  to  the  spray  treatments.  Fortunately, 
the  three  spray  program  with  the  lime-sulphur  was  carried  out  in 
duplicate,  the  two  rows  being  widely  separated  in  the  experiment 
plot.  One  of  these  rows  had  small  fruit,  but  it  was  very  apparent 
that  this  was  due  to  the  fact  that  the  trees  were  subnormal  in  point 
of  vigor.  The  other  row  receiving  the  same  treatment  consisted  of 
normal  trees,  and  the  fruit  at  harvest  time  was  found  to  be  normal 
in  every  respect. 

One  row  (see  footnote,  Table  III)  was  sprayed  on  May  25,  after 
the  fruit  was  nearly  grown,  with  an  8-8-50  solution  of  self -boiled 
lime-sulphur.  This  material  had  a  very  marked  effect  on  the  fruit. 
Practically  every  apricot  that  was  at  least  half  covered  with  the  spray 
ceased  to  develop.  It  was  very  apparent  that  this  spray,  which  is 
in  universal  use  for  controlling  brown  rot  in  peaches  in  the  eastern 
and  southern  states,  cannot  safely  be  used  on  apricots  after  the  fruit 
has  set. 

YIELD    AND    GRADES    OF    SPRAYED    APRICOTS 

All  the  fruit  in  the  experiment  orchard  ran  small  in  size,  owing 
to  the  inadequate  supply  of  soil  moisture  early  in  the  season.  At 
the  close  of  the  winter  rains  the  ground  was  wet  down  only  about 
thirty  inches.  The  orchard  was  irrigated  May  15,  the  earliest  date 
at  which  it  was  possible  to  procure  water,  and  again  June  15,  but 
apparently  the  trees  needed  water  early  in  order  to  make  the  proper 
growth  and  put  size  on  the  fruit.  The  experiment  apricots  were 
harvested  in  three  pickings,  that  is,  on  July  12,  18,  and  24.  The 
fruit  from  each  tree  under  the  different  treatments  was  separately 
weighed  and  graded  at  each  picking.  Only  two  grades  were  recog- 
nized, that  which  was  acceptable  to  the  cannery  and  that  which  was 
not.  The  cannery  would  accept  no  fruit  smaller  than  fourteen  to  the 
pound;  all  fruit  under  this  size  had  to  be  dried.  For  convenience 
these  two  grades  are  designated  as  No.  1  and  No.  2.  The  results 
of  the  grading  are  summarized  in  Table  V. 


Bulletin  326  BROWN  ROT  OF  APRICOTS  83 

TABLE  V 

Average  Yield  per  Tree  and  Percentage  of  Fruit  of  Cannery  Grade  and 

Below  Cannery  Grade  Produced  Under  the  Different 

Spray  Treatments 

Av.  yield 

per  tree,  Percentage  Percentage 

Row  Spray  treatment  lbs.  No.  1  fruit  No.  2  fruit 

1  Unsprayed*     95.5  93.80  6.20 

2  Three   lime-sulphur   sprays.... 50.5  3.33  96.67 

3  Linie-sulphur     once;     as     buds     were 

swelling   46.0  22.82  77.18 

4  Bordeaux  once;  as  buds  were  swelling       51.16  65.94  34.06 

5  Lime-sulphur  once;  as  buds  were  open- 

ing           63.00  71.58  28.42 

6  Lime-sulphur    once;    as    flowers    were 

falling    83.16  88.78  11.22 

7  Bordeaux  once;  as  buds  were  opening     104.83  51.51  48.49 
7a  Unsprayedf     102.72                 76.86  23.13 

8  Three   lime-sulphur   sprays 79.00  70.68  29.32 

9  Ortho   crude   oil  once;    as   buds   were 

much   swollen   103.00  84.96  15.04 

10  Weak  Bordeaux   once;    as   buds   were 

swelling   78.00  78.64  21.36 

11  Three  dry  lime-sulphur   sprays 92.5  26.53  73.47 

12  Dry  lime-sulphur  once;    as  buds  were 

opening    57.00  30.11  69.89 

13  Weak  Bordeaux  once;  as  flowers  were 

falling    89.83  43.42  56.58 

14  Sulphur    dust  twice;    as   flowers   were 

falling    176.13  72.25  27.75 

15  Unsprayed 115.23  80.27  19.73 

16  Distillate  emulsion  once;  as  buds  were 

swelling    125.50  90.29  9.71 

17  Three  weak  lime-sulphur  sprays 77.83  22.92  77.08 

18  Lime  whitewash  once;  as  flowers  were 

falling 153.83  79.64  20.36 

19  One    application    self-boiled    lime-sul- 

phur, May   25 70.33  23.22  76.78 

20  Unsprayed*     73.5  92.31  7.69 

*  Outside  row. 

f  This  row  was  made  up  of  the  end  tree  of  all  sprayed  rows. 

From  the  yield  records  shown  in  Table  V  it  might  be  inferred 
that  spraying  does  not  protect  the  fruit  sufficiently  to  increase  the 
yield.    This  was  true  in  the  experiment  under  discussion,  as  the  brown 


84 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


rot  was  not  bad  enough  in  this  orchard  to  affect  the  yield  materially. 
Even  though  numerous  flower  clusters  were  destroyed  and  many 
fruiting  spurs  killed,  the  set  of  fruit  on  the  healthy  wood  that 
remained  was  sufficient  to  make  a  full  crop.  Unfortunately,  many 
of  the  trees  were  weak  from  inadequate  irrigation  in  previous  years 
and  from  a  shortage  in  soil  moisture  in  April  and  early  May  of  this 


Fig.  4. — Apricot  mummy  remaining  on  the  tree  and  producing  fresh  spore 
pustules  the  following  spring.  Pustules  are  seen  with  especial  clearness  near  the 
stem.  The  spores  are  very  small  and  a  great  number  are  formed  on  a  single 
pustule  and  carried  away  by  the  wind.     May  5,  1915. 


season,  so  that  the  fruit  did  not  size  properly.  Also  it  was  realized 
too  late  that  many  of  the  trees,  particularly  the  weaker  ones,  were  not 
thinned  heavily  enough. 

Owing  to  the  light  attack  of  the  brown  rot  in  the  experiment 
orchard,  the  yield  records  must  be  studied  not  with  a  view  to  deter- 
mining whether  the  disease  itself  reduced  the  yield — for  we  know 
it  did  not — but  to  determine  whether  the  sprays  caused  the  fruit  to 


Bulletin  326 


BROWN  ROT  OF  APRICOTS 


85 


be  undersized  or  late  in  ripening.  The  fact  has  been  well  established 
(Tables  I  and  II)  that  spraying  will  reduce  the  disease  by  more 
than  90  per  cent,  and  there  is  every  reason  to  believe  that  this  rate 
of  control  will  hold  just  as  true  when  the  disease  infection  is  heavy 
as  when  it  is  light. 

Row  I,   unsprayed,   was   an  outside   row,   and   consequently  con- 
tained better  than  average  trees,  yet  there  was  considerable  variation 


Fig.  5. — Brown  rot  cankers  in  almond  branches  from  twig  blight  the  previous 
spring.  Pustules  of  new  spores  are  forming  on  the  old  cankers.  A  mass  of  gum 
shows  on  the  lower  twig.     April,  1920. 


in  size  and  vigor,  and  the  yield  per  tree  varied  from  40  to  149  pounds. 
Still,  there  was  enough  extra  good  fruit  on  the  best  trees  to  bring  the 
yield  of  No.  1  apricots  to  93.8  per  cent,  the  highest  of  any  row  in  the 
experiment.  Incidentally,  one  of  the  trees  in  this  row — the  best  one 
— ripened  its  fruit  among  the  latest  in  the  orchard. 

Row  2,  sprayed  three  times  with  lime-sulphur,  contained  some  very 
poor  trees.  They  were  somewhat  undersized  and  appeared  to  have 
made  but  little  growth  in  the  past  two  years.  They  not  only  aver- 
aged smaller  than  those  in  Row  1,  but  were  not  so  vigorous.     This 


86  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

was  one  of  the  rows  that  was  not  thinned  enough.  As  a  result,  all  the 
fruit  was  small.  Row  2,  however,  was  among  the  first  in  the  orchard 
to  be  harvested.  The  fruit  matured  early  because  the  trees  were 
weak. 

Row  8  was  also  sprayed  three  times  with  lime-sulphur,  but  the 
trees  were  normal  in  size  and  vigor  and  they  ripened  their  fruit  along 
with  other  trees  of  comparable  size  and  condition.  This  row  was  about 
equal  in  every  way  to  Row  7,  which  was  sprayed  with  Bordeaux. 
While  the  yield  of  Row  8  was  not  so  great  as  that  of  Row  7,  the  per- 
centage of  No.  1  fruit  was  much  higher — 70.6  as  compared  with  51.5. 

There  has  been  no  question  of  injury  to  the  fruit  from  Bordeaux 
mixture.  Taking  rows  4  and  7,  both  Bordeaux  sprayed,  it  is  seen 
that  they  show  a  decidedly  lower  percentage  of  No.  1  fruit  than 
rows  5  and  6,  sprayed  with  lime-sulphur.  Rows  2  and  3  are  excluded 
from  the  comparisons  on  account  of  too  many  weak  trees.  Observa- 
tion of  the  sprayed  trees  certainly  showed  no  indication  of  injury 
from  either  the  lime-sulphur  or  the  Bordeaux  mixture. 

EXPERIENCE    OF   GROWERS 

Numerous  growers  in  the  Santa  Clara  Valley,  have  sprayed 
apricots  with  lime-sulphur  against  brown  rot.  The  experience  of  one 
of  these,  Joe  Seitz,  located  two  miles  northwest  of  Mountain  View 
near  the  State  highway,  is  the  most  instructive.  Mr.  Seitz  has  sprayed 
his  ten-acre  orchard  for  four  successive  years  as  follows :  in  1917, 
just  before  the  trees  came  into  bloom,  with  lime-sulphur  1-10 ;  in  1918 
the  same ;  in  1919  with  lime-sulphur  1-30  just  after  the  bloom ;  and 
in  1920  twice  before  the  bloom  with  1-10  and  once  after  with  1-30. 
He  reports  having  always  controlled  the  disease  within  reasonable 
limits,  without  causing  injury  to  the  fruit.  He  will  continue  to 
spray  hereafter,  but  thinks  that  one  application  of  lime-sulphur  1-10, 
before  the  bloom,  is  sufficient.  An  apricot  orchard  immediately 
adjoining  that  of  Mr.  Seitz  has  never  been  sprayed  against  brown 
rot,  and  has  suffered  very  severely  from  the  disease  every  year. 

Contrasted  with  the  above  is  the  case  of  D.  C.  Bache,  of  Hamilton 
Avenue,  near  Campbell,  who  reports  having  sprayed  his  apricots  in 
the  spring  of  1920  as  follows :  One  part  of  the  orchard  received  lime- 
sulphur  1-12  and  another  part  1-14  as  buds  were  much  swollen  but 
not  showing  pink,  and  again  received  the  same  solutions  as  trees  were 
passing  out  of  bloom.  Still  another  part  of  the  orchard  was  sprayed 
once  with  lime-sulphur  1-20,  and  a  final  part  with  1-30,  both  as 
trees  were  passing  out  of  bloom.     He  considers  that  all  these  sprays 


Bulletin  326  BROWN  ROT  OF  APRICOTS  87 

were  very  effective  in  controlling  the  brown  rot,  but  thinks  that  all 
caused  the  fruit  to  be  small  and  late  in  ripening,  and  that  spraying 
before  the  bloom  was  more  harmful  than  after  the  bloom.  This 
orchard  was  examined,  and  the  fruit  certainly  was  small  and  late  in 
ripening.  From  the  appearance  of  the  trees  and  the  treatment  they 
had  received  this  season,  the  trouble  could  not  be  attributed  to  lack 
of  moisture  in  the  soil;  but  the  history  of  the  orchard  for  the  past 
two  seasons  could  not  be  obtained,  as  Mr.  Bache  had  just  purchased 
the  ranch.  Hereafter  Mr.  Bache  will  spray  with  Bordeaux  mixture, 
as  he  does  not  consider  the  peach  twig  borer,  which  causes  wormy 
apricots  in  so  many  orchards,  a  serious  problem. 

Several  other  orchards  have  been  noted  by  Mr.  Bache  as  having 
small  fruit  this  season.  He  attributed  the  cause  to  spraying  with 
lime-sulphur,  but  on  examination  the  trouble  seemed  clearly  to  have 
been  caused  by  lack  of  moisture  in  the  soil.  In  some  instances  the 
trouble  seemed  to  date  back  to  the  treatment  received  during  the 
previous  season  or  during  the  past  two  years. 

CUTTING    OUT   DISEASED  TWIGS 

Blighted  twigs  and  mummied  fruits  that  remain  on  the  trees 
through  the  fall  and  winter  give  rise,  in  the  spring,  to  a  new  crop 
of  brown  rot  spores.  These  spores  on  twigs  and  mummies  are  the 
principal  known  sources  of  brown  rot.  Accordingly,  some  time  before 
the  buds  swell,  all  mummies  and  all  affected  twigs  should  be  cut  out 
and  burned. 

It  would  have  been  impractical  to  remove  all  affected  twigs  when 
the  disease  first  broke  out  or  while  it  was  still  active,  owing  to  the 
difficulty  or  impossibility  of  telling  where  the  diseased  wood  left  off 
and  the  healthy  wood  began.  If  the  diseased  wood  is  not  all  removed, 
the  labor  of  cutting  out  the  twigs  may  be  lost,  or,  on  the  other  hand, 
unnecessary  damage  to  the  tree  may  result  from  heavy  pruning  to 
make  certain  all  affected  parts  are  removed. 

An  experiment  in  cutting  out  the  diseased  twigs  soon  after  the 
appearance  of  the  disease  was  tried  on  the  John  Losse  ranch  in  Santa 
Clara  Valley.  The  trees  were  large  and  in  a  fine  state  of  vigor.  The 
tops  were  rather  dense,  but  fruit  spurs  were  numerous  throughout. 
The  attack  of  brown  rot  was  severe,  most  of  the  twigs  being  affected. 
On  March  24,  after  the  disease  had  apparently  ceased  to  be  active, 
every  affected  twig  on  two  trees  was  cut  out.  The  injured  area, 
however,  extends  farther  along  the  interior  of  the  twig  than  on  the 
outside.      Hence,   although   great   care   was   taken — even   to   making 


50  UNIVERSITY  OP  CALIFORNIA EXPERIMENT  STATION 

two  or  three  cuts — observations  made  ten  days  later  showed  that  the 
disease  had  continued  to  develop  in  from  40  to  50  per  cent  of  the 
twigs.  A  second  cutting*  was  necessary  to  rid  the  tree  of  all  affected 
twigs,  and  even  this  was  not  completely  successful. 

The  object  of  removing  the  diseased  twigs  so  early  in  the  season 
was  to  determine  whether  such  treatment  would  protect  the  ripe  fruit 
from  being  attacked  by  the  rot.  Observations  made  at  harvest  time, 
however,  showed  as  much  rot  in  the  trees  where  the  twigs  had  been 
removed  as  where  they  had  not.  It  appears  therefore  that  fruit  rot 
cannot  be  prevented  by  cutting  out  the  diseased  twigs,  but  twig 
blight,  it  is  believed,  can  be  as  effectively  and  more  easily  controlled 
by  removing  them  in  the  fall  or  winter  as  by  cutting  them  out  in 
the  spring. 

It  is  believed  to  be  worth  while  to  remove  all  affected  twigs  when 
the  regular  pruning  is  done,  in  order  to  prevent  the  disease  from  being 
carried  over  the  winter.  At  the  same  time  every  mummied  fruit 
should  be  collected  from  the  trees  and  from  the  ground,  and  both 
twigs  and  mummies  destroyed  by  burning. 

Confusion  with  Peach  Blight. — During  the  past  year  there  has 
been  some  confusion  between  brown  rot  and  the  diseases  caused  by 
the  peach  blight  fungus,  Coryneum  beyerinckii.  The  peach  blight 
fungus  is  active  during  the  wet  weather  of  winter  and  spring.  On 
apricots  it  causes  winter  killing  of  buds  or  bud  blight,  shot-hole  disease 
on  the  early  leaves,  and  small  corky  spots  on  young  green  fruit. 
Peach  blight  fungus  causes  serious  losses  in  the  interior  valleys  and 
foothills  but  is  rarely  serious  in  the  coast  districts,  whereas  brown  rot 
is  confined  almost  entirely  to  the  coast  regions.  Treatment  for  peach 
blight  fungus  on  peaches  and  apricots  consists  in  spraying  with 
winter  strength  lime-sulphur  solution  or  Bordeaux  mixture  in  Novem- 
ber or  early  December  and  again  as  the  buds  swell  in  the  spring. 
Some  growers  have  been  giving  the  spray  in  November  to  apricots 
in  the  coast  districts,  but  this  is  evidently  unnecessary  in  nearly  all 
cases  near  the  coast. 


STATION   PUBLICATIONS   AVAILABLE   FOE   FREE   DISTRIBUTION 


BULLETINS 


No. 

185. 

251. 

253. 

257. 
261. 
262. 

263. 
266. 

267. 
268. 
270. 


271. 
272. 
273. 

274. 

275. 

276. 
278. 
279. 
280. 

282. 

283. 
285. 
286. 


Report  of  Progress  in  Cereal  Investiga- 
tions. 

Utilization  of  the  Nitrogen  and  Organic 
Matter  in  Septic  and  Imhoff  Tank 
Sludges. 

Irrigation  and  Soil  Conditions  in  the 
Sierra  Nevada  Foothills,  California. 

New  Dosage  Tables. 

Melaxuma  of  the  Walnut,  "  Juglans  regia." 

Citrus  Diseases  of  Florida  and  Cuba 
Compared  with  Those  of  California. 

Size  Grades  for  Ripe  Olives. 

A  Spotting  of  Citrus  Fruits  Due  to  the 
Action  of  Oil  Liberated  from  the  Rind. 

Experiments  with  Stocks  for  Citrus. 

Growing  and  Grafting  Olive  Seedlings. 

A  Comparison  of  Annual  Cropping,  Bi- 
ennial Cropping,  and  Green  Manures 
on  the  Yield  of  Wheat. 

Feeding  Dairy  Calves  in  California. 

Commercial  Fertilizers. 

Preliminary  Report  on  Kearney  Vine- 
yard Experimental  Drain. 

The  Common  Honey  Bee  as  an  Agent  in 
Prune  Polination. 

The  Cultivation  of  Belladonna  in  Cali- 
fornia. 

The  Pomegranate. 

Grain  Sorghums. 

Irrigation  of  Rice  in  California. 

Irrigation  of  Alfalfa  in  the  Sacramento 
Valley. 

Trials  with  California  Silage  Crops  for 
Dairy  Cows. 

The  Olive  Insects  of  California. 

The  Milch  Goat  in  California. 

Commercial  Fertilizers. 


No. 

288. 

290. 

298. 
299. 
300. 
301. 

302. 

303. 
304. 

308. 


309.  I 

310. 
311. 
312. 
313. 
316. 
317. 
318. 
319. 
320. 
321. 
322. 
323. 

324. 

325. 


Potash  from  Tule  and  the  Fertilizer 
Value  of  Certain  Marsh  Plants. 

The  June  Drop  of  Washington  Navel 
Oranges. 

Seedless  Raisin  Grapes. 

The  Use  of  Lumber  on  California  Farms. 

Commercial  Fertilizers. 

California  State  Dairy  Cow  Competition, 
1916-18. 

Control  of  Ground  Squirrels  by  the 
Fumigation  Method. 

Grape  Syrup. 

A  Study  on  the  Effects  of  Freezes  on 
Citrus  in  California.  _ 

I.  Fumigation   with    Liquid    Hydrocianic 
Acid.     II.  Physical  and  Chemical  Pro- 
perties of  Liquid  Hydrocianic  Acid. 
The   Carob  in   California.     II.  Nutri- 
tive Value  of  the  Carob  Bean. 

Plum  Pollination. 

Investigations  with  Milking  Machines. 

Mariout  Barley. 

Pruning  Young  Deciduous  Fruit  Trees. 

The  Kaki  or  Oriental  Persimmon. 

Selections  of  Stocks  in  Citrus  Propagation. 

The  Effects  of  Alkali  on  Citrus  Trees. 

Caprifigs  and  Caprification. 

Control  of  the  Coyote  in  California. 

Commercial  Production  of  Grape  Syrup. 

The  Evaporation  of  Grapes. 

Heavy  vs.  Light  Grain  Feeding  for  Dairy 
Cows. 

Storage  of  Perishable  Fruit  at  Freezing 
Temperatures. 

Rice  Irrigation  Measurements  and  Ex- 
periments in  Sacramento  Valley,  1914- 
1919. 


CIRCULARS 


No. 

70.  Observations    on    the    Status     of    Corn 

Growing  in  California. 
76.  Hot  Room  Callusing. 
82.  The     Common     Ground      Squirrels      of 

California . 

113.  Correspondence  Courses  in  Agriculture. 

114.  Increasing  the  Duty  of  Water. 

115.  Grafting  Vinifera  Vineyards. 

117.  The  Selection  and  Cost  of  a  Small  Pump- 
ing Plant. 
124.  Alfalfa  Silage  for  Fattening  Steers. 

126.  Spraying  for  the  Grape  Leaf  Hopper. 

127.  House  Fumigation. 

128.  Insecticide  Formulas. 

129.  The  Control  of  Citrus  Insects. 

130.  Cabbage  Growing  in  California. 

131.  Spraying  for  Control  of  Walnut  Aphis. 

135.  Official  Tests  of  Dairy  Cows. 

136.  Melilotus  Indica. 

137.  Wood  Decay  in  Orchard  Trees. 

138.  The  Silo  in  California  Agriculture. 

139.  The  Generation  of  Hydrocyanic  Acid  G  ^,s 

in  Fumigation  by  Portable  Machines. 

140.  The    Practical   Application    of    Improved 

Methods  of  Fermentation  in  California 
Wineries  during  1913  and  1914. 

143.  Control     of     Grasshoppers    in     Imperial 

Valley. 

144.  Oidium  or  Powdery  Mildew  of  the  Vine. 
148.   "Lungworms". 

152.  Some  Observations  on  the  Bulk  Handling 

of  Grain  in  California. 

153.  Announcement    of    the    California    State 

Dairy  Cow  Competition,  1916-18. 

154.  Irrigation     Practice     in     Growing     Small 

Fruits  in  California. 

155.  Bovine  Tuberculosis. 


No. 

156.  How  to  Operate  an  Incubator. 

157.  Control  of  the  Pear  Scab. 

158.  Home  and  Farm  Canning. 

159.  Agriculture  in  the  Imperial  Valley. 

160.  Lettuce  Growing  in  California. 

164.  Small  Fruit  Culture  in  California. 

165.  Fundamentals    of    Sugar    Beet    Culture 

under  California  Conditions. 

167.  Feeding  Stuffs  of  Minor  Importance. 

168.  Spraying  for  the  Control  of  Wild  Morning- 

Glory  within  the  Fog  Belt. 

169.  The  1918  Grain  Crop. 

170.  Fertilizing  California  Soils  for  the   1918 

Crop. 

172.  Wheat  Culture. 

173.  The  Construction  of  the  Wood-Hoop  Silo. 

175.  Progress  Report  on  the  Marketing  and 

Distribution  of  Milk. 

176.  Hog  Cholera  Prevention  and  the  Serum 

Treatment. 

177.  Grain  Sorghums. 

178.  The  Packing  of  Apples  in  California. 

179.  Factors  of  Importance  in  Producing  Milk 

of  Low  Bacterial  Count. 

181.  Control  of  the  California  Ground  Squirrel. 

182.  Extending  the  Area  of  Irrigated  Wheat  in 

California  for  1918. 

183.  Infectious  Abortion  in  Cows. 

184.  A  Flock  of  Sheep  on  the  Farm. 

185.  Beekeeping  for  the  Fruit-grower  and  Small 

Rancher  or  Amateur. 

187.  Utilizing  the  Sorghums. 

188.  Lambing  Sheds. 

189.  Winter  Forage  Crops. 

190.  Agriculture  Clubs  in  California. 

191.  Pruning  the  Seedless  Grapes. 


CIRCULARS — Continued 


No. 

193.  A  Study  of  Farm  Labor  in  California. 
198.  Syrup  from  Sweet  Sorghum. 

201.  Helpful  Hints  to  Hog  Raisers. 

202.  County     Organization     for     Rural     Fire 

Control. 

203.  Peat  as  a  Manure  Substitute. 

204.  Handbook    of   Plant    Diseases    and    Pest 

Control. 

205.  Blackleg. 

206.  Jack  Cheese. 

207.  Neufchatel  Cheese. 

208.  Summary  of  the  Annual  Reports_of  the 

Farm  Advisors  of  California. 
210.  Suggestions  to  the  Settler  in  California. 

213.  Evaporators  for  Prune  Drying. 

214.  Seed    Treatment    for    the    Prevention    of 

Cereal  Smuts. 


No. 
215.  Feeding  Dairy  Cows  in  California. 

217.  Methods    for    Marketing    Vegetables    in 

California. 

218.  Advanced  Registry  Testing  of  Dairy  Cows. 

219.  The  Present  Status  of  Alkali. 

220.  Unfermented  Fruit  Juices. 

221.  How  California  is  Helping  People  Own 

Farms  and  Rural  Homes. 

222.  Fundamental  Principles  of  Co-operation 

in  Agriculture. 

223.  The  Pear  Thrips. 

224.  Control  of  the  Brown  Apricot  Scale  and 

the  Italian  Pear  Scale  on  Deciduous 
Fruit  Trees. 

225.  Propagation  of  Vines. 

226.  Protection    of    Vineyards    from    Phyl- 

loxera. 


